How do the kidneys work?
The body takes nutrients from food and converts them to energy. After the body has taken the food that it needs, waste products are left behind in the bowel and in the blood.
The kidneys and urinary system keep chemicals, such as potassium and sodium, and water in balance by removing a type of waste, called urea, from the blood. Urea is produced when food containing protein, such as meat, poultry, and certain vegetables, are broken down in the body. Urea is carried in the bloodstream to the kidneys.
Two kidneys, a pair of purplish-brown organs, are located below the ribs toward the middle of the back. Their function is to:
- Remove liquid waste from the blood in the form of urine
- Keep a stable balance of salts and other substances in the blood
- Produce erythropoietin, a hormone that aids the formation of red blood cells
The kidneys remove urea from the blood through tiny filtering units called nephrons. There are about one million nephrons in each kidney, located in the medulla and the cortex. Each nephron consists of a ball formed of small blood capillaries, called a glomerulus, and a small tube called a renal tubule.
Urea, together with water and other waste substances, forms the urine as it passes through the nephrons and down the renal tubules of the kidney. Urine collects in the calyces and renal pelvis and moves into the ureter, where it flows down into the bladder.
In addition to filtering waste from the blood and assisting in the balance of fluids and other substances in the body, the kidneys perform other vital functions. These functions include:
- Production of hormones that help to regulate blood pressure and heart function
- Conversion of vitamin D into a form that can be used by the body’s tissues
What is nephrology?
Nephrology is the branch of medicine concerned with the diagnosis and treatment of conditions related to the kidneys. Other health professionals who treat kidney problems include primary care doctors, pediatricians, and urologists.
What causes problems with the kidneys?
In children, problems of the urinary system include acute and chronic kidney failure, urinary tract infections, obstructions along the urinary tract, and abnormalities present at birth.
Diseases of the kidneys often produce temporary or permanent changes to the small functional structures and vessels inside the kidney. Frequent urinary tract infections can cause scarring to these structures leading to renal (kidney) failure. Some diseases that cause kidney damage include:
- Hemolytic uremic syndrome
- Polycystic kidney disease
- Urinary tract infections
Disorders of the genitourinary system in children are often detected by fetal ultrasound prior to birth. If not detected on fetal ultrasound, often children will develop a urinary tract infection that will prompt your child's doctor to perform special diagnostic tests that may detect an abnormality. Some diseases of the kidney do not reveal themselves until later in life or after a child has a bacterial infection or an immune disorder.